Circuit breaker operating system



Jan. 20, 1942. s' uFmKv 2,270,353 CIRCUIT BREAKER OPERATING SYSTEM Filed Jan. 8, 1940 TRIO-J l! E g RECLOS/N- 7 a z/ Inventor:

Robert- M. Spur-CK is Attorney.

Patented Jan.v 20, 1942 CIRCUIT BREAKER OPERATING SYSTEM Robert M. Spurck, Llanerch, Pa., assignor to General Electric Company, a corporation of New York Application January 8, 1940, Serial No. 312,974 9 Claims. (Cl. 175-294) My invention relates to circuit breaker operating systems, more particularly to pneumatic systems for effecting high speed automatic reclosure of a circuit breaker, and has for its principal object the provision of an improved circuit breaker operating. and reclosing system of the aforesaid type that is rapid, positive and eflicient in operation, that has low input power rating, and that is applicable to large circuit breakers requiring a considerable closing force.

A further object of my invention is the provision of an improved pneumatic automatic circuit breaker reclosing system that is effective to apply the reclosing force in a positive manner and without delay at a predetermined inter-,

mediate point in the breaker opening stroke.

In electric distribution systems where continuity of service is a very important factor,

means have been provided for quickly reclosing an electric circuit breaker one or more times after automatic opening in response to a fault on the assumption that a very large percentage of faults, such as surges due to lightning, for example, are of a temporary nature. In synchronized circuits, however, such reclosusres must be made at very high speed if the synchronous.

to open a circuit and clear faults, but also to.

maintain the circuit clear in the open circuit position under adverse voltage conditions. That is, the length of stroke of the circuit breaker must be sufficient not only to interrupt the heaviest currents for which the breakeris rated, but also to prevent restriking of the arc in case the line voltage is several times that of normal. As contrasted with this isolating function of the breaker, it should be borne in mind that a well designed breaker can actually clear a fault within a few inches of opening stroke.

In accordance with the present invention, a

fluid motor, such as a piston and cylinder arfor rapidly reclosing it after a tripping operation with minimum expenditure of gas energy.

My invention will be more fully set forth in the following description referring to the accompanying drawing; and the features of novelty which characterize my invention will be pointed out with particularity in the claims annexed to and forming'a part of this specification.

Referring to the drawing, the single figure thereof is a partly diagrammatic layout of a high speed automatic circuit breaker operating and reclosing system embodying the present invention.

The pneumatic operating mechanism illustrated by way of example comprises a fluid motor I of the piston and cylinder type, a source of compressed gas 2 for operating the motor and a circuit breaker operating member 3 that is operatively connected by a flexible linkage 4 to the piston 5 of the fluid motor. The circuit breaker (not shown) can in the present instance conveniently be of the gas blast type by reason of the source of compressed gas 2, although it will be apparent that any suitable type can be used.

In the position shown, the circuit .breaker operating member or rod 3 is held by means hereinafter described 'in the closed circuit position, a compression spring 6 biasing the breaker and mechanism toward open circuit position. The operating means interconnecting the breaker rod 3 and the piston 5 may be of any suitable type, the specific chain linkage arrangement herein shown being of the character described and claimed in Thumim Patent 2,112,054, granted ranged for example for pneumatic operation, is

connected to a source of gas pressure, such as pivotally mounted at 8' and is biased in a counter-clockwise direction by a spring 8"so as to ride over and engage a pin 9 secured to the piston rod 5'.

The chain linkage l is particularly adapted for applications requiring movement of 'the circuit breaker operating rod at right angles to the direction of operating force and is held in operative position by a crank it that is pivotally mounted .at H and is provided with rollers l2 and It at the extremities of the crank arms. The roller 2 storage tank for closing a circuit breaker and I2 serves as a rolling guide for the chain linkage 4, and the roller I3 cooperates with a pivoted latch N that is in turn associated with a tripping solenoid l5. The latch I4 is spring biased at Ii in counter-clockwise direction so that it can reset beneath the roller l3 and the crank I is also biased counter-clockwise by a spring ll for the purpose of stretching the chain 4 and returning the crank to a reset position with respect to the latch I4. As shown, the crank II is held against rotation by the latch |4 so that the linkage 4 is under tension for holding the breaker 3 in closed circuit position.

A more detailed description of the chain linkage mechanism is believed to be unnecessary other than to point out that upon clockwise movement of the latch H in response to actuation of the tripping solenoid IS, the breaker spring 6 causes rotation of the crank II clockwise, taking up slack in the chain 4 and thereby permitting opening movement of the breaker rod. Upon initial clockwise rotation of the crank ID, the prop 3 is also pushed away from the pin roller 9 by reason of a camming action at II between the crank Ill and an extension ll of the prop 8.

The piston can now'move to its upper position for producing more slack in the chain 4 allowing complete opening of the breaker and permitting resetting of the crank ll under influence of its spring II. The breaker is now open and the mechanism reset and in*readiness for a closing operation.

To initiate the closing operation of this type mechanism, gas under pressure is admitted to the cylinder I9 by'a control valve 20 for moving the piston 5 downward. Thecrank M, which is now reset and in the position shown, holds the chain linkage taut so that the breaker rod 3 is moved by the piston against the bias of opening spring 3 to the closed circuit position shown. When the piston reaches its lower' limit of travel, the prop 8 snaps over the pin roller 3 and holds the breaker in closed circuit position independently of the fluid motor I. The normal tripping operation is as above described, that is, energization of the tripping solenoid IS in response to a fault condition in the circuit, for example, causes release of the latch I4 and collapse of the chain linkage 4 so as to permit opening movement of the breaker.

It will be noted that the operating mechanism above described is trip-free during the closing operation of the breaker. That is, tripping of the latch l4 prior to complete closing of the breaker is effective to cause immediate opening movement of the breaker notwithstanding continued closing movement of the piston 5.

The operating mechanism so far described is adapted for the normal circuit closing and opening operations wherein the breaker operating member is moved throughout its full stroke for each operation. In the case 0! high speed reclosing however, it is essential that the breaker reclosing movement be initiated after but a fraction of the normal opening stroke as previously pointed out. To this end, the fluid motor is controlled by the valve 23 so that a fresh charge of compressed gas is admitted to the cylinder ll after predetermined opening of the breaker so that the piston i is immediately driven back to its fully closed position. The cylinder ll furthermore is so vented that the space at the'working side of the piston still contains gas under reduced pressure so that the fresh charge of gas can act with maximum speed on the piston I. That is, since the cylinder space is not completely exhausted, as in the case prior to a normal closing operation, a comparatively small charge of compressed gas under source pressure. quickly raises the cylinder pressure to accomplish at high speed the desired reclosing stroke.

The control means for accomplishing high speed reclosing comprise an auxiliary switch 2| arranged to control energization of the valve operating solenoid 22, and means hereinafter described for controlling tripping of the chain linkage mechanism at the latch I4. The auxiliary or reclosing switch 2| is arranged to be engaged by a cam or the like 3 secured to the breaker rod 3 for closing the switch 2| when the breaker rod has moved a predetermined distance toward open circuit position. This distance corresponds to the length of stroke for clearing the fault. The switch 2| is connected so as to be in series with a manual reclosing control switch 23 that is mechanically connected to a tripping switch 24.

When the reclosing cycle is to be used, the switch 23 is in the position shown and upon opening movement of the breaker the energizing circuit of the valve solenoid 22 is completed from the source of control voltage indicated through the reclosing control switch 23, reclosing switch 2|, source pressure control switch 25, and limit or cutofi switch 26. The switch 25 is for the purpose of rendering the system inoperative in case of failure of the gas source pressure at 2, and the switch 26 automatically deenergizes the valve solenoid when the piston 5 completes its working stroke and reaches the closed circuit position. Upon deenergization of the solenoid 22, a biasing spring 22"'returns the valve 20 to the closed position shown.

It now it be assumed that the breaker is in the closed circuit position shown and the reclosing control switch 23 is closed, energization of the fault relay FR in response to a fault current or overload on the power circuit indicated at 21 causes closing of the fault relay contacts at 28 to energize through the contacts 29 of the transfer relay TR, the tripping solenoid 30. This tripping solenoid is directly associated with the pivoted prop 3 so that upon actuation of the solenoid plunger 33', the prop is kicked in clockwise direction so as to release the piston 5 and permit' mined initial opening movement of the breaker rod 3, the reclosing switch 2| is closed in the manner previously described to cause energization of the valve solenoid 22 and opening of the valve 2.. Immediately upon opening of the valve, the piston I is driven back through a partial working stroke to the position shown, resulting in immediate reclosure of the breaker. As previously pointed out, this action can be very fast since the cylinder space above the piston is already filled with gas when the reclosing operation is initiated.

For the p p se of providing trip-free protection during the reclosing operation, the tripping relay TR. The transfer relay as a result switches the tripping circuit from contact 29 to contact 32 so that the tripping solenoid I is now in the trippin circuit instead of the tripping solenoid 30. The circuit is maintained at contact 32 by a suitable dashpot device for a time suflicient to permit exhaust of gas from the cylinder I9 after,

the reclosing operation. A transfer relay system of this character isdisclosed and claimed in a copending application Serial No. 192,782, flied February 26, 1938 by C. Thumim for High speed reclosing mechanism and assigned to the same assignee as the present invention. Since as above pointed out, the tripping solenoid I5 is in the tripping circuit during the reclosing operation, persistence of the fault on the line will cause actuation of the trip-free solenoid at It as the fault relay FR closes its contacts at 28. The latch ll then releases the crank in to permit opening of the breaker in the manner previously described.

The resetting of the mechanism then takes place in the manner above described, the piston spring 5" raising the piston 5 as the gas in the cylinder space is vented through the valve controlled opening and the spring I! -of the crank i0 taking up the slack in the chain 4 until the crank roller I3 is latched at II. The prop 8 lies alongside the left side of the pin 9 as viewed so as, to be in readiness to latch the piston at the lower limit of its closing stroke.

During the reclosing cycle above decribed, the manual switch C is closed as well as the reclosing control switch 23. With the breaker in the closed circuit position, manual control of trip- Pi is efiected merely by closing the tripping switch 24 which automatically causes opening of the switch 23. The circuit breaker is then tripped at the solenoid in the manner previously described. The closing operation is initiated by opening the switch ,24 thereby causing closing of switch 23, assuming that the'switch C is also closed. The energizing coil 22 of the valve solenoid is then energized through the reclosing control switch 23, switch C and the auxiliary switches 25 and 26.

It should be understood that my invention is not limited to specific details of construction and arrangement thereof herein illustrated, and that changes and modifications may occur to one skilled in the art without departing from the spirit of my invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. An automatic reclosing'circuit breaker system comprising a fluid motor, a source of fluid under pressure, a control valve for admitting said fluid to said motor for operating the circuit breaker to closed circuit position, trippin means for causing opening of said circuit breaker, and

means operative in response to predetermined.

circuit opening movement of said circuit breaker for opening said valve and causing reclosing of said circuit breaker by means of a partial working stroke of said breaker prior to completion of the full opening stroke of said breaker.

2. An automatic reclosing circuit breaker system comprising a fluid motor for operating the circuit breaker to closed circuit position, sprin means arranged to be stressed by said fluid motor for biasing said circuit breaker toward open circuit position, a source of fluid under pressure for operating said motor, a control valve between said source and motor, tripping means for releasing stored energy in said spring means for causing opening movement of said circuit breaker, and means operable by and in accordance with predetermined opening movement of said circuit breaker for causing opening of said valve and actuation of said fluid motor to reclose said circuit breaker prior to completion of the opening stroke thereof.

3. An automatic reclosing circuit breaker system comprising an operating piston, means interconnecting the circuit breaker and said piston including trip-free means, a spring for biasing said circuit breaker toward open circuit position, a source of fluid under pressure for operating said piston so as to cause closing movement of said circuit breaker against the bias of said spring, a control valve between said source and piston, a second tripping means independent of said first-named tripping means for releasing said spring and causing. opening movement of both said piston and said circuit breaker, and means operable by and in accordance thereof.

, between said source and piston,'a latch for releasing said piston and spring for initiating opening movement of said circuit breaker, reclosing means operable in response to predetermined opening movement of said circuit breaker for opening said valve whereby the movement of said piston is instantly reversed and the circuit breaker is reclosed. prior to completion of the opening stroke thereof, and means for releasing said trip-free connection for causing opening of said circuit breaker in the event that said reclosing operation is concurrent with a circuit fault.

5. An automatic reclosing circuit breaker system comprising an operating cylinder and piston, a trip-free connection between said piston and the circuit breaker, a spring for biasing said circuit breaker toward open circuit position, a source of gas under pressure for operating said piston so as to cause closing movement of said circuit breaker against the bias of said spring, a control valve between said source and cylinder for selectively. admitting gas to and venting said cylinder, a second tripping means for releasing .said spring and causing opening movement of ing movement of said circuit breaker for causing opening of said valve and reversal of said piston under source gas pressure to reclose said circuit breaker prior to completion of the opening stroke thereof.

6. An automatic reclosing circuit breaker system-comprising a source of gas under pressure, a fluid motor having a cylinder and piston, a control valve between said source and cylinder, means operatively connecting said piston and the circuit breaker, spring means arranged to bias said circuit breaker and also said piston toward open circuit position, said spring means being stressed in accordance with the circuit closing movement of said piston, tripping means for causing opening movement of said circuit breaker I and said piston, said cylinder being vented to ex haust approximately at the end of the piston closing stroke whereby reverse initial opening movement of said piston can also take place at high speed, said control valve in the closed position thereof also arranged to vent said cylinder through a restricted opening, and means for opening said valve at a predetermined intermediate point in the opening stroke of said breaker for admitting gas under source pressure to the aforesaid vented cylinder space for reclosing said circuit breaker prior to completion of the opening stroke thereof.

- 7. An automatic reclosing circuit breaker system comprising a source ofv gas under pressure a fluid motor having a cylinder and piston, means operatively connecting said piston to the circuit breaker, valve means for controlling admission of gas from said source to said cylinder to cause closing of said circuit breaker, fault responsive means for causing opening of said circuit breaker and reverse movement of said piston, said piston after initial high speed opening movement thereof causing closing of cylinder venting means, the cylinder working space thereupon being vented through said valve means, and means operable in response to predetermined circuit opening movement of said breaker to cause closing of the valve vent and opening of said valve for admitting gas under source pressure directly to said cylinder working space whereby the opening movement of said piston is instantly reversed and said circuit breaker to completion or its opening stroke.

is reclosed prior a 8. An automatic. reclosing circuit breaker system comprising a source of gas under pressure, a fluid motor having a cylinder and piston, means operatively connecting said piston to the circuit breaker, a solenoid-operated valve for controlling admission of gas from said source to said cylinder to cause closing of said circuit breaker, latching means for holding said circuit breaker and piston in closed circuit position against an opening spring bias, fault responsive means coacting with said latching means for causing opening 01 said circuit breaker and reverse movement of said piston, the cylinder working space being vented for initial high speed opening movement of said piston, and electroresponsive means operable upon predetermined circuit opening movement of said breaker to cause opening of said valve for admitting gas under source pressure directly to said cylinder working space whereby the opening movement of said piston is instantly reversed and said circuit breaker is reclosed prior to completion of its opening stroke.

9. An automatic reclosing circuit breaker system comprising a source of gas under pressure, a fluid motor having a cylinder and piston, means operatively connecting said piston to the circuit breaker, valve means for controlling admission of gas from said source to said cylinder tocause closing of said circuit breaker, fault responsive means for causing opening of said circuit breaker and reverse movement of said piston, means for facilitating high speed opening movement of said piston including a venting passage for the cylinder working space controlled by said valve means, and means operable in response to predetermined circuit opening movement of said breaker to cause closing of the valve controlled vent and opening or said valve for admitting gas under source pressure directly to said cylinder working space whereby the opening movement of said piston is instantly reversed and said circuit breaker is reclosed prior to completion of its opening stroke. 4

ROBERT M. SPURCK. 

